Helium is the second most abundant element in the Universe. Yet, it is not the most abundant on Earth - Why?
Helium atoms are small and cannot be retained by the Earth's gravitational field.
Helium accounts for up to 23 percent by mass of the Universe and the Sun. It is the most abundant element in the universe after hydrogen; Helium is rare in the atmosphere because its atoms are small and travel fast enough to escape the pull of Earth’s gravitational field. Do note that all the other noble gases occur in the atmosphere. There is no primordial Helium. In other words, there was no Helium from before the formation of Earth.
That leaves us with the question – where does the Helium on Earth come from? Helium comes into existence as α particles from radioactive decay and tends to accumulate in natural gas deposits.